cachepc

commit 039144b8e7f7fb4074883e8037787d420e86f70c
parent 7cd66755ff29a9f56601d5612a902b45d14798d5
Author: Louis Burda <quent.burda@gmail.com>
Date:   Wed,  1 Feb 2023 12:20:58 -0600

fixup! Event batching

Diffstat:
M
Makefile
 | 
2
+-
M
README
 | 
4
++--
M
cachepc/event.c
 | 
23
+++++++++--------------
M
cachepc/uapi.h
 | 
15
++++++++-------
M
test/kvm-step.c
 | 
1
+
D
test/qemu-pagestep
 | 
0

6 files changed, 21 insertions(+), 24 deletions(-)
diff --git a/Makefile b/Makefile
@@ -44,7 +44,7 @@ linux: # build host kernel for depmod
 	git -C $(LINUX) stash
 	git -C $(LINUX) checkout d9bd54fea4d2
 	rm -f $(LINUX)/arch/x86/kvm/cachepc
-	$(MAKE) -C $(LINUX) -j $(JOBS) -l $(LOAD)
+	$(MAKE) -C $(LINUX) -j $(JOBS) -l $(LOAD) vmlinux headers
 	git -C $(LINUX) checkout master
 	git -C $(LINUX) stash pop || true
 
diff --git a/README b/README
@@ -69,13 +69,13 @@ CPC_TRACK_EXIT_EVICTION:
 	measurements over a clean run to a guest-invoked exit such as KVM_EXIT_HLT.
 
 CPC_TRACK_PAGES:
-	Track execution of all guest pages. While the guest is running untrack
+	Track execution of all guest pages. While the guest is running, untrack
 	a single executable page at a time based on page-faults. Allows tracking
 	which guest pages are executed and how long using retired instructions.
 
 CPC_TRACK_STEPS:
 	Single-step guest exection. For each step, collect either only instruction
-	or instruction and page-faults. Allows tracking not only which sets were
+	or instruction and data page-faults. Allows tracking not only which sets were
 	evicted but what gfns were involved in the access. A target page can
 	be set, such that we will first page-step until the page is reached,
 	then single-step while running instructions on that page.
diff --git a/cachepc/event.c b/cachepc/event.c
@@ -71,6 +71,7 @@ cpc_send_event(struct cpc_event event)
 
 	if (cpc_event_batching) {
 		if (cpc_eventbuf_len < CPC_EVENTBUF_CAP) {
+			event.id = 0;
 			memcpy(&cpc_eventbuf[cpc_eventbuf_len], &event,
 				sizeof(struct cpc_event));
 			cpc_eventbuf_len++;
@@ -84,7 +85,7 @@ cpc_send_event(struct cpc_event event)
 	}
 
 	cpc_last_event_sent++;
-	event.id = cpc_last_event_sent;
+	cpc_event.id = cpc_last_event_sent;
 	cpc_event_avail = true;
 
 	write_unlock(&cpc_event_lock);
@@ -193,23 +194,17 @@ cpc_poll_event_ioctl(void __user *arg_user)
 {
 	int err;
 
-	read_lock(&cpc_event_lock);
+	write_lock(&cpc_event_lock);
 	if (!cpc_event_avail) {
-		read_unlock(&cpc_event_lock);
+		write_unlock(&cpc_event_lock);
 		return -EAGAIN;
 	}
-	read_unlock(&cpc_event_lock);
 
 	err = 0;
-	write_lock(&cpc_event_lock);
-	if (cpc_event_avail) {
-		if (copy_to_user(arg_user, &cpc_event, sizeof(cpc_event)))
-			err = -EFAULT;
-		else
-			cpc_event_avail = false;
-	} else {
-		err = -EAGAIN;
-	}
+	if (copy_to_user(arg_user, &cpc_event, sizeof(cpc_event)))
+		err = -EFAULT;
+	else
+		cpc_event_avail = false;
 	write_unlock(&cpc_event_lock);
 
 	return err;
@@ -245,7 +240,7 @@ cpc_ack_event_ioctl(void __user *arg_user)
 int
 cpc_read_events_ioctl(void __user *arg_user)
 {
-	struct cpc_event_batch batch;
+	struct cpc_batch_event batch;
 	size_t n;
 
 	if (!arg_user) return -EINVAL;
diff --git a/cachepc/uapi.h b/cachepc/uapi.h
@@ -30,7 +30,7 @@
 
 #define KVM_CPC_POLL_EVENT _IOWR(KVMIO, 0x40, struct cpc_event)
 #define KVM_CPC_ACK_EVENT _IOWR(KVMIO, 0x41, __u64)
-#define KVM_CPC_READ_EVENTS _IOWR(KVMIO, 0x42, struct cpc_event_batch)
+#define KVM_CPC_READ_EVENTS _IOWR(KVMIO, 0x42, struct cpc_batch_event)
 
 #define KVM_CPC_VM_REQ_PAUSE _IO(KVMIO, 0x50)
 
@@ -93,6 +93,12 @@ struct cpc_guest_event {
 	__u64 val;
 };
 
+struct cpc_batch_event {
+	__u64 cnt;
+	__u64 maxcnt;
+	struct cpc_event *buf;
+};
+
 struct cpc_event {
 	__u32 type;
 	__u64 id;
@@ -100,15 +106,10 @@ struct cpc_event {
 		struct cpc_track_step_event step;
 		struct cpc_track_page_event page;
 		struct cpc_guest_event guest;
+		struct cpc_batch_event batch;
 	};
 };
 
-struct cpc_event_batch {
-	__u64 cnt;
-	__u64 maxcnt;
-	struct cpc_event *buf;
-};
-
 struct cpc_sev_cmd {
 	__u32 id;
 	__u64 data;
diff --git a/test/kvm-step.c b/test/kvm-step.c
@@ -146,6 +146,7 @@ main(int argc, const char **argv)
 			if (ret && errno == EAGAIN) continue;
 			if (ret) err(1, "KVM_CPC_POLL_EVENT");
 
+			printf("%lu\n", event.id);
 			if (event.type == CPC_EVENT_PAUSE) break;
 
 			ret = ioctl(kvm_dev, KVM_CPC_ACK_EVENT, &event.id);
diff --git a/test/qemu-pagestep b/test/qemu-pagestep
Binary files differ.